Eculizumab is a humanized monoclonal antibody that binds with high affinity to C5. The drug is FDA-approved for the treatment of paroxysmal nocturnal hemoglobinuria (in which mutations of complement regulatory proteins on hematopoietic cells lead to alternative complement pathway-mediated hemolysis). It is currently being studied for use in atypical hemolytic uremic syndrome, a rare disease marked by diffuse microthromboses related to activation of the alternate complement system. Eculizumab prevents cleavage of C5, thereby precluding formation of C5a, which has been implicated in glomerular inflammation in animal models of DDD. Moreover, by inhibiting the activation of C5, it prevents formation of the membrane attack complex C5-9. Speculatively, this drug could provide effective, targeted therapy for patients with DDD.